iTunes 7.7 pre-release seed is being provided solely for the purpose of installing iPhone OS beta 8 on your Apple devices. The use of this pre-release software is governed by the same non-disclosure agreement covered in your Registered iPhone Developer Terms and Conditions with Apple. iTunes 7.7 pre-release software is for development and testing purposes only and therefore should not be used with any existing iTunes libraries on your system.

Request new iPhone Development Certificate
To prepare for the release of iPhone OS 2.0, certificates issued prior to June 9, 2008 have been
revoked. Request new iPhone Development Certificates in the Program Portal and have a Team
Admin re-generate any provisioning profiles containing the revoked certificates.

Looks like AppStore won't work without the latest version of iTunes installed. Developers are now encouraged to submit their apps for review - the last we heard they were able to submit the metadat, but uploads were not yet working for the actual apps.

The OS 2.0 Beta 8 firmware is NOT the Golden Master that some sites had rumored was released, but that firmware version will still be released by early July, as Steve let us know in the last keynote.

Also of interest - the usual RAM disk decryption is no longer possible in beta 8. The dev team and hacking community will have to figure this one out in the next couple weeks before launch.

This is unverified, but the tipster also sent us this blurb from the Whats New in iTunes 7.7:

What's new in iTunes 7.7
Use iTunes 7.7 to sync music, video, and more with iPhone 3G, and download applications from the iTunes Store exclusively designed for iPhone and iPod touch with software version 2.0 or later. Also use the new Remote application for iPhone or iPod touch to control iTunes playback from anywhere in your home — a free download from the App Store.

This could be confirmation of the rumor that's been going around on the Remote application which lets you control iTunes with the iPhone.

Further iTunes 7.7 info:

I may be too late, but you may want to add this that I forgot to include in the tip:

When I launched iTunes 7.7 I found that it introduces MobileMe settings under the Info Tab and a new Application syncing tab.
The MobileMe settings redirects you to the browser to a http page at Apple, but it is currently unavailable.

iTunes Store behaves as usual. No App Store or link so far.

On a side note: I now have an iPhone with 2.0 Beta 5A345, but surprisingly my other iPhone with 2.0 Beta 5A240d that is Pwned, is now recognized as a regular iPhone and not with the generic iPod icon. Nevertheless, music downloaded from iTunes still won’t sync because it reports that the software is too old.

So far the usual tricks I used to downgrade from 5A331 (Beta 7) to 1.1.4 are apparently not working. Thus for the moment I am stuck with Beta 8 on one of my devices.